CVD-grown tunable carbon films for high-performance sodium storage

Sodium-ion batteries are considered a promising and sustainable energy-storage technology, yet achieving competitive energy density requires electrode materials with high reversible capacity. Here, we introduce a chemical vapor deposition strategy that allows the growth of uniform, electronically continuous carbon coatings onto highly porous carbon substrates for use as high-capacity negative electrodes. This coating narrows and partially seals the open pore network, suppresses surface reactivity, and establishes nanoconfined domains that allow sodium to be stored in a more compact manner. This restructuring significantly enhances sodium storage performance, delivering total reversible capacities exceeding 500 mAh g^-1 together with an unprecedented 420 mAh g^-1 reversible plateau capacity. By enabling control over heteroatom composition, confinement, and electronic structure, this approach not only addresses the challenge of designing uniform and electronically continuous carbon coatings on highly porous substrates but also establishes a general route for designing functional carbon films for advanced electrodes, catalysts, and interfaces with tunable electronic properties.